key terms

Efficiency of biomass transfer:

The efficiency of biomass transfer between trophic levels is calculated using:

Extremophiles

\: Organisms that can live in extreme environments e.g. high temperatures, high salinity

Food chain:

\: Describes the feeding relationships between organisms and the resultant stages of biomass transfer. It takes the form: producer ⟶ primary consumer ⟶ secondary consumer ⟶ tertiary consumer

\*Food security:

Ensuring that populations have access to adequate amounts of safe and nutritious food

Global warming

The gradual rise in the average temperature of the Earth due to increasing atmospheric levels of carbon dioxide and methane gas.

\*GM crops

\: Crops that have had their genomes modified by the insertion of a desired gene from another organism.

Interdependence:

The dependence of different organisms on each other for survival e.g. plants depend on pollinators, herbivores depend on plants.

Microorganisms

\: Very small organisms involved in the recycling of materials in an ecosystem. They return mineral ions to the soil and convert carbon to carbon dioxide which is released into the atmosphere

Active transport:

The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration.

Adult stem cell:

\: A type of stem cell that can form many types of cells.

Agar jelly

A substance placed in petri dishes which is used to culture microorganisms on

Cell differentiation:

The process where a cell becomes specialised to its function.

Cell membrane:

\: A partially permeable barrier that surrounds the cell.

Cell wall

An outer layer made of cellulose that strengthens plant cells

Chloroplast:

An organelle which is the site of photosynthesis.

Chromosomes

DNA structures that are found in the nucleus which are made up of genes.

Concentration gradient:

The difference in concentration between two areas.

Diffusion:

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration

Embryonic stem cell:

A type of stem cell that can differentiate into most types of human cells.

Eukaryotic cell

\: A type of cell found in plants and animals that contains a nucleus.

Magnification:

How much bigger an image appears compared to the original object

Meristematic cells

A type of stem cell that can differentiate into any type of plant cell.

Mitochondria

\: An organelle which is the site of respiration.

Mitosis:

A type of cell division which produces two genetically identical daughter cells from one parent cell.

Nucleus:

An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell.

Organelle:

A specialised structure found inside a cell.

Osmosis:

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Plasmid

Loops of DNA found in the cytoplasm of prokaryotic cells.

Prokaryotic cell

A type of cell found in bacteria that does not contain a nucleus.

Resolution:

The ability to distinguish two different points in a specimen

Specialised cells:

Cells that are adapted to perform a specific function.

Stem cell:

An undifferentiated cell that can divide to produce many specialised cells of the same type

Surface area:

\: The amount of contact an object has with its environment

Surface area to volume ratio (SA:V)

\: The size of the object compared with the amount of area where it contacts its environment.

The cell cycle

\: A series of stages preparing the cell for division.

Therapeutic cloning:

Producing an embryo that has the same genes as a patient.

Vacuole:

\: An organelle that stores cell sap.

Amylase

An enzyme produced in the salivary glands and pancreas that breaks carbohydrates down into simple sugars.

Aorta

The main artery that takes oxygenated blood away from the heart to the body.

Artery:

A blood vessel that carries blood at high pressure away from the heart

Benign tumour

An abnormal cell growth that is contained within one area and does not invade other areas of the body.

Bile:

A substance made in the liver and stored in the gallbladder which is used to neutralise stomach acid in the intestine and emulsify fats.

Blood:

A tissue containing red blood cells, white blood cells, platelets and plasma. Cancer: A non-communicable disease caused by changes in the cell that lead to uncontrolled growth and division.

Capillary:

\: A very thin blood vessel that is used for exchange of substances.

Cell:

The basic building block of all living organisms.

Communicable disease:

\: A disease that can be spread between individuals either directly or indirectly.

Coronary heart disease

A disease caused by the buildup of fatty deposits inside the coronary artery, narrowing it and reducing blood flow to the heart tissue.

Enzymes

Biological catalysts that increase the rate of reactions in living organisms

Health:

The state of physical and mental wellbeing.

Heart:

An organ that pumps blood around the body in a double circulatory system.

Lipase

An enzyme that is produced in the pancreas that breaks lipids down into fatty acids and glycerol.

Lock and key hypothesis:

A theory that describes how substrates must be the correct shape to fit the active site of an enzyme.

Malignant tumour

A cancerous cell growth that invades neighbouring tissues and can spread to different parts of the body in the blood

Meristem tissue

Plant tissues containing undifferentiated stem cells

Metabolism

All of the chemical reactions occurring in an organism

Non-communicable disease

A disease which cannot be spread between individuals.

Organs:

Aggregations of tissues performing specific functions

Organ systems

Groups of organs that work together to form organisms

Palisade mesophyll:

A tissue found in plant leaves that is specialised to carry out photosynthesis.

Phloem

A transport tissue found in plants which is specialised to transport sugars from source to sink.

Protease

An enzyme produced in the stomach and pancreas that breaks proteins down into amino acids.

Pulmonary artery:

The main artery that takes deoxygenated blood away from the heart to the lungs

Pulmonary vein:

\: The main vein that takes oxygenated blood back to the heart from the lungs

Rate of reaction

The speed at which reactants are converted into products.

Risk factor:

Something that increases a person’s risk of developing a disease.

Spongy mesophyll:

A tissue found in plant leaves that is specialised for gas exchange.

Statins:

A class of drugs that are used to reduce blood cholesterol levels which slows down the rate of fatty material deposit

Stent

A tube that can be surgically implanted into blood vessels to keep them open.

Tissue

A group of cells with a similar structure and function.

Translocation:

The movement of food molecules through the phloem tissue

Transpiration:

The process of water evaporating from a plant

Vein:

A blood vessel that carries blood at a low pressure back to the heart.

Vena cava

The main vein that takes deoxygenated blood back to the heart from the body.

Xylem

A transport tissue in plants which is specialised to transport water and dissolved minerals from the roots of the plant to the leaves.

Antibiotics

\: Medicines that help to cure bacterial disease by killing infective bacteria inside the body.

Clinical drug testing:

Drug testing done on healthy human volunteers and patients.

Communicable disease

A disease that can be spread between individuals either directly or indirectly

Double blind trial:

A study performed where neither the researcher or patient know whether the patient is taking the drug or a placebo.

Gonorrhoea:

A sexually transmitted disease (STD) caused by a bacterium with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating

Human Immunodeficiency Virus (HIV):

\: An infectious virus that weakens the immune system and can lead to AIDS (acquired immunodeficiency syndrome).

Malaria:

A disease caused by a protist that causes recurrent episodes of fever and can be fatal.

Measles

A serious disease caused by a virus that shows symptoms of fever and a red skin rash.

\*Monoclonal antibodies

Antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen.

Non-communicable disease:

A disease which cannot be spread between individuals

Non-specific defence

General physical and chemical barriers that defend the body against lots of different types of pathogen.

Pathogens:

Microorganisms that cause infectious disease.

Placebo

\: A substance designed to be indistinguishable from a drug being tested but has no actual effect on the patient.

Preclinical drug testing

Drug testing done in a laboratory using cells, tissues and live animals.

Rose black spot:

A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early.

Salmonella:

\: A bacterial disease that is spread by bacteria ingested in food and can cause a fever, abdominal cramps, vomiting and diarrhoea.

Side effects

Other additional effects that the drug has that are different from the expected effect of the drug

Tobacco Mosaic Virus (TMV)

A widespread plant pathogen affecting many species of plants which produces a mosaic pattern on the leaves and limits the plant growth.

Vaccination:

\: The process of introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.

White blood cell

An important type of cell that makes up the immune system and produces antibodies and antitoxins.

Aerobic respiration:

\: A form of respiration that uses oxygen to release energy from molecules like glucose -

Anaerobic respiration

\: A form of respiration that releases energy from molecules like glucose without using oxygen

Cellular respiration

An exothermic reaction which is continuously occurring in living cells.

Inverse proportion

A relationship between two values where as one value increases, the other value decreases at the same rate.

Inverse square law:

\: As the distance from a light source increases, the light intensity is inversely proportional to the distance squared

Limiting factor:

A factor that limits the rate of a reaction when there is not enough of it